1. Field of the Invention
The present invention relates to a measurement system.
2. Description of the Related Art
A measurement system is described in EP 0 661 543 B1. It includes an acceleration sensor in the form of a Ferraris sensor, wherein a magnetic flux passes vertically through an electrically conducting disk, constituting the measuring structure. This magnetic flux is generated by a magnet. If the disk is moved with respect to the magnet, eddy currents are created, which in turn generate a magnetic field. The changes in this magnetic field, or flux, are detected by a detector in the form of a coil and are a measure for the acceleration. An optically or inductively scannable scale graduation is fixed on the edge of this disk and is scanned by a scanning head for determining the position of this disk.
It is therefore an object of the present invention to design a measurement system with an acceleration sensor and a position sensor in such a way that as compact a structure as possible is achieved.
This object is attained by a measurement system for determining acceleration and a position of an object. The measurement system includes a first sensor system for determining an acceleration of an object, the first sensor system having a body with an electrically conducting measuring structure, a device for generating a first magnetic field, which acts on the measuring structure and a detector for detecting a second magnetic field or field changes, which are created by eddy currents generated by the measuring structure, the detector generating an output signal. A second sensor system for determining a position of the object, the second sensor system includes a scale graduation that lies opposite the detector and is scanned by the detector in a scanning area in which the measuring structure and the scale graduation are arranged placed on top of each other, or integrated into each other, and wherein the detector generates an acceleration signal and a position signal from a common scanning area. The measuring structure and the scale graduation are formed on a common body.
The measurement system of the present invention has the advantage that the scale graduation required for the position measurement is provided directly on the measuring structure for the acceleration measurement and is therefore arranged in a space-saving manner. The acceleration signal and the position signal are here derived from a common scanning area. It is realized that no scanning areas which are located transversely with respect to the measuring direction are required.
Advantageously the electrical properties of the measuring structure of the acceleration sensor are not affected by the scale graduation. The scale graduation of the acceleration sensor can be realized in a separate layer, or in a layer package, which is connected with the measuring structure of the acceleration sensor in such a way that the measuring structure can expand independently of the layers supporting the scale graduation.
It is alternatively possible to embody the scale graduation in the measuring structure itself, wherein it is then necessary to make provisions, such as signal filtering, signal smoothing, multiplexing, or switching between several detectors, or averaging, in order to keep the acceleration signal as unaffected as possible by the measuring representation.
The present invention will be explained in greater detail in what follows by the drawings. Shown are in: